This section provides background information related to the present disclosure which is not necessarily prior art.
Strut-type suspension systems are well known in the motor vehicle industry. A telescopic strut normally incorporating a hydraulic damper is used as one of the locating members for the wheel of the motor vehicle. The most common form of a strut-type suspension is the McPherson strut suspension system. The McPherson strut assembly includes a coil spring located concentrically around the telescopic strut which is the shock absorber. The upper end of the McPherson strut assembly includes an upper mounting assembly which is mounted in a tower formed by the vehicle body at a position above the wheel arch of the vehicle.
The coil spring is located around the shock absorber and it extends between an upper spring seat which is a part of the top mount assembly for the strut assembly and a lower spring seat which is attached, typically by welding, to the shock absorber of the strut assembly. The spring seats of the strut assembly have several functions for the suspension system. The spring seats support and maintain the correct position of the spring and support the loading on the spring under all driving conditions of the vehicle for the entire life of the vehicle. The spring seats are mechanically resistant during the life of the vehicle. They resist braking loads, deformations, wear, abrasion, changing loads and hits by stones and other debris. The spring seat is environmental and corrosion resistant to different temperatures, different moisture levels, aggressive liquids and gasses. The spring seats ensure proper fixing of the components of the strut assembly, easy assembly of the strut assembly into the vehicle and with the other components of the strut assembly they resist any unwanted displacements and/or rotations. The design of the spring seats also ensure that the spring to spring seat contact does not promote or accelerate corrosion of the spring or the spring seat.
The prior art lower spring seats typically include a single piece formed spring seat. The single piece spring seat has a contoured portion that mates with the terminal end of the spring and a flanged portion that is welded to the outer tube of the shock absorber of the strut assembly. These single piece lower spring seats have restrictions with the shape forming process, restrictions in the design for reinforcing the spring seat, difficulties with the assembly to the shock absorber, issues relating to water, sand, dust and other debris retention, issues relating to cooperation with other components of the strut assembly and suspension assembly and they are relatively heavy due to their single piece design.